Venetian blinds having a headrail and blind slats extending horizontally across a window space are well known. It is well understood that the width of the headrail and the blinds must be suited to more or less match to the width of the window space.
For many years it has been the practice to manufacture venetian blinds on a custom basis. Each blind would be made with the width of the headrail, and the blade width corresponding to the width of a particular window for a particular customer.
This procedure is however relatively expensive. A salesperson is required to attend the customer's house, in most cases, and take a series of measurements. An order is then placed at the factory, and some weeks later the finished blinds are delivered to the customer. Clearly it would be desirable to manufacture a range of venetian blinds, which could be arranged to fit window spaces having a range of widths. However given the limitation of the design, this is simply not possible. In order to partly answer the problems of cost, and delay, of custom made venetian blinds, it would be desirable to manufacture venetian blinds in a range of stock widths, and in a limited range of colours, and stocking these blinds in retail outlets. A customer wishing to purchase a blind or blinds from such an outlet would simply come in with the measurements of the windows of the customer's house. The customer would select those blinds which were as close to the measurements as possible, or only slightly wider.
The retail store would then trim the ends of the blind to the width desired by the customer. The system would mean that the blinds could be manufactured in larger production runs, thus reducing the cost. It would also mean that customers could purchase blinds and take them away from the store almost on a same day basis. There are however certain problems with this procedure.
In particular the design of venetian blinds requires at least two and in some cases more, raise cords, and tilt cords. These cords are arranged at equal distances from each side of the blind. Consequently, trimming the blind to width required trimming each side, by an amount equal to one half of the desired total trim amount, so as to ensure the blind had a satisfactory symmetrical appearance. However, the blind consists of three main different components namely, a headrail, usually of U-shaped metal channel, a bottom rail and set of blind slats, the number depending on the height of the window opening. In the vast majority of cases the blind slats were formed with a curved cross-section, and the ends of the blind slats were usually cut with a slight bevel or radius, so as to avoid sharp corners at each end of each blind slat.
End trimming operations could not be carried out by simple hand tools. Specialized dies were required for cutting each separate shape, i.e. for cutting the headrail and for cutting the bottom rail and for cutting the slat ends which were of arcuate cross-section with bevelled corners.
Specialized dies and tools have been provided for the purpose, but, it was necessary for each retail store to be carefully trained so as to carry out the three separate cutting operations in a way which produced a blind which was symmetrical down each side.
One minor improvement on the situation was that certain manufacturers provided a cutting die for cutting both the headrail and the bottom rail simultaneously. In this system it was only necessary to provide a separate cut for the blade ends.
Even in this system however, there were possibilities for mistakes, and the operator required considerable skill. The cutting operation was also time consuming.
For all of these reasons, it is clearly desirable to provide an end cutting method for cutting the sides of venetian blinds, in which all three components namely, the headrail, the bottom rail and the blind slats are all cut in a single apparatus. In this way the time required in the retail store for the end cutting operation is reduced. In addition, the skill required is reduced since all three components are in a single plane.
Certain venetian blinds are available having blind slats, and a bottom rail made of material which is wider, in some cases two inches wide. While the headrail, and the blind slats in this type of blind are still made of metal, the bottom rail is frequently made of non-metallic material. This is usually a solid, flat bar which may be for example be formed by extruding thermoplastic materials, or may even be made of wood in some cases, although this is not usual.
Similar requirements may also arise in connection with vertical blinds. In this case the blind has a headrail, and control rods within the headrail. It may be advantageous to trim these components at the point of sale for example, in order to adjust the width of the blind to the requirements of a customer. There is in this case no bottom rail and the vertical slats have a predetermined height which is not trimmed. However, depending on the length of the headrail that is to be trimmed off, it may be necessary to remove one or more vertical blind slats, and runners, from the headrail.